BEIRUT — Clashes between Syrian rebels and their rivals from an al-Qaida-linked faction spread on Monday from the country's opposition-held areas in the north to a key eastern city, activists said.
The rebel-on-rebel fighting in the eastern city of Raqqa — a long-time bastion of an al-Qaida-linked group known as the Islamic State in Iraq and the Levant — reflects a widening war within a war in Syria, this one against radical extremists.
It also suggests emboldened rebels are trying to completely overrun their al-Qaida rivals. The infighting has been the most serious since armed groups initially rose to try overthrow the rule of Syrian President Bashar Assad.
The clashes erupted in the northern provinces of Aleppo and Idlib on Friday after residents there accused ISIL fighters of killing a popular doctor.
An activist group, the British-based Syrian Observatory for Human Rights estimated that at least 100 fighters on both sides have been killed since Friday.
The rebels fighting against ISIL are an unruly series of moderate and ultra-conservative groups who have little to unite them, save for their hatred of the al-Qaida group. ISIL is dominated by foreign fighters who initially fanned into Syria from neighboring Iraq in March and muscled into areas that rebels wrested from Assad-loyal forces, imposing their deeply conservative interpretation of Islamic law.
Tensions against ISIL fighters had been simmering for months. Rebels accused them of overtaking their areas, seizing their weapons and detaining their fighters. They have also eroded the good will of the locals by imprisoning Syrian civilians for perceived transgressions against their deeply conservative interpretation of Islam, and detained activists and journalists critical of their rule.
A coalition of Islamic brigades began clashing with ISIL forces in Raqqa overnight and the fighting continued Monday, said Rami Abdurrahman, the director of the Observatory. Another activist group, the Local Coordinating Committees, also reported the Raqqa clashes, saying they were focused around a city post office.
The Observatory said rebels had surrounded ISIL's chief compound in Raqqa and had liberated at least 50 detainees from a nearby prison. Abdurrahman said they included fighters and activists who were imprisoned for their criticism of ISIL.
The freed prisoners appeared to include fighters of another Islamic group, the Tawheed Brigade. In a video uploaded to social networks, one of their fighters is seen shouting, "apostates, apostates, they are just Muslims in name!"
There was also infighting in the nearby town of Tal Abyad, the Observatory said.
Raqqa was the first city to fall entirely into the hands of rebels, and was seized by ISIL last year. Since then, rumors have swirled that foreign aid workers, reporters and Syrian activists have been held in Raqqa's prisons.
Even as the fighting spread, another al-Qaida-linked rebel group, the Nusra Front, said it was trying to mediate to halt the rebel infighting. The Syrian-dominated extremist group has largely stayed away from the infighting. In updates posted to its Twitter feed, the Nusra Front offered protection for any rebel fearing for his safety.
But rebels of the more moderate Syrian Revolutionary Front — a recently formed coalition of rebel brigades aligned with the exiled Syrian opposition — appeared reluctant to give up their offensive.
In a statement Monday, they demanded ISIL fighters desert the al-Qaida group and join their ranks. They also accused ISIL of killing at least 400 of their fighters and imprisoning 2,000 since ISIL emerged.
"Were it not for these actions, the Front would not have raised its weapons," the statement said.
So far, the rebels appear to have taken several ISIL compounds in the northern province of Aleppo.
Also in Aleppo, ISIL fighters handed over their strongholds in the town of Tal Rafat to the Nusra Front to avoid clashes, the Observatory reported.
Rebels and ISIL fighters were also clashing in the town of Jarablous near the Syria-Turkey border. ISIL had seized key border crossings from the rebels over the past months.
Associated Press writer Zeina Karam contributed to this report from Beirut.
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